Friday, June 03, 2005

Genetic Link?

Apparently, a team of scientists have published a paper proposing that a group of genetic diseases common in Jews of Ashkenazic origin can be linked to a higher intellectual ability in the same population.

In describing what they see as the result of the Ashkenazic mutations, the researchers cite the fact that Ashkenazi Jews make up 3 percent of the American population but won 27 percent of its Nobel prizes, and account for more than half of world chess champions...The researchers have identified two reasonably well accepted issues, the puzzling pattern of diseases inherited by the Ashkenazi population and the population's general intellectual achievement.

Interesting. But as Steven Pinker, a cognitive scientist at Harvard states in the article:

It would be hard to overstate how politically incorrect this paper is.

Wow, this kind of reasoning is incredibly fraught with pitfalls. Right off the bat, I'd disagree that people in managerial positions and moneylenders would be more inclined to have lots of kids. From an evolutionary perspective, it makes more sense to have a lot of kids if you work the land - there's a direct correlation between agricultural output and hands on the job. In the so-called "smart" fields, however, extra mouths to feed eventually become competitors, since the niche is not big enough to support all these new operators (kind of like the mortgage business and Lakewood). So the inclination over the long run would actually be to reduce breeding - the opposite effect. A religious imperative to breed would dampen this, and there certainly is one in Judaism - but I dont think it would do so entirely. Also, I very much question the notion that these diseases are good at creating more neuronal connections - they are ultimately very neurotoxic. The paper is VERY fuzzy as to how this positive effect could occur. What bugs me about this is that while the classical genetic diseases that confer a protective effect from some infectious agent -like sickle cell and malaria, or cystic fibrosis and cholera - had direct evolutionary pressure from an infectious agent - its a lot harder (and less accurate) to quantify things like socioeconomic evolutionary pressure - since it's so tenuous an effect.

The corollary to this, however, would be that since the 1700's, when the range of professional options for Jews broadened considerably, we've been slowly breeding back to baseline - in other words, getting stupider. THAT would explain much.

It is most definitely NOT weak science -- it provides a radical testable hypothesis, namely that heterozygote carriers for sphingolipid diseases will tend to have higher g, on the order of 5 IQ points. If this hypothesis proves to be true, it's implausible that their thesis is wrong.

"Right off the bat, I'd disagree that people in managerial positions and moneylenders would be more inclined to have lots of kids."

There are data on this point, see Weinryb's JEWS OF POLAND. It is also well known since the efforts of the sociobiologists in the 70s and 80s that wealthy people had more children than poor people everywhere in Europe, in fact everywhere anyone has ever looked _except_ in societies after the demographic transition to lower mortality and lower fertility that started in the late 18th century in Europe.

" Also, I very much question the notion that these diseases are good at creating more neuronal connections - they are ultimately very neurotoxic."

Take a look at the occupations of Ari Zimran's patients with Gaucher disease, and remember that these are the third to half of people with the disease in Israel: the rest aren't sick enough to seek medical care.

"Also, I wonder how many shul rabbis are going to triumphantly make a big deal out of this article while conveniently ignoring the fact that its based on evolutionary biology (gasp!)..."

huh? it is based on the same concepts as horse breeding. Creationists don't argue against evolution of traits *within* species. The concept of nishtane hateva MEANs evolutions within species. It's actually a wonderful demonstration of the concept for the shul rabbi.

I don't know wht the fuss is about; everyone Jewish knows that Jews have been selectively breeding for intelligence for centuries.

Dr. Harpending, I think you slight the "Talmudic scholarship model" - there is tons of evidence for it, formal and informal. Speak to anyone who studies Jewish midieval life. The wealthy actively sought to marry Talmud scholars and daughters of such (it's actually a Torah commandment to do so), and this increased their status in the community and their influence and connections. In additions, scholars married among themselves, and were given tax relief, supported through difficult times, etc. (Although the class of "professional" scholars was limited, as you say, they had higher survival rates than average.)

"I'm not sure wherher to be jealous of Sefardim - they're disease free, but they're dumb."

I don't quite buy that Sephardim are the same IQ as the general population; I'm sure that there are differences between Sephardim from different areas and that the picture will turn out to be more complex.

"Dr. Harpending, I think you slight the "Talmudic scholarship model" - there is tons of evidence for it, formal and informal. Speak to anyone who studies Jewish midieval life. "

You may be right. My bias is to look at demographic and other data wherever possible and to pay less attention to to "common knowledge" when I don't have real data. But absence of evidence is not evidence of absence: my dream is that a research assistant fluent in medieval Polish and Yiddish will show up at my office door one day.

It is clear from the literature that I found that medieval Ashkenazi had a classic hypergynous dowry system like all the rest of the aristocracy (I am talking about 1200 now, not 1700). In these systems roughly speaking families of women buy their way into the husbands' families with large dowries. Everywhere these have been described they are based on wealth alone: upper class India for example still has a lot of this. They are called "hypergynous" because typically females marry up: these are daughters of "nouveax riches" families who can outbid upper class families. The typical result is a surplus of women at the top, and family honor prevents them from marrying down.

These systems are all firmly based on money, and there doesn't seem to be much room for things like attractiveness. But my reasoning is entirely by analogy with other hypergynous dowry systems that have been well described and I would not be displeased at all to be proven wrong.

"You may be right. My bias is to look at demographic and other data wherever possible and to pay less attention to to "common knowledge" when I don't have real data... my dream is that a research assistant fluent in medieval Polish and Yiddish will show up at my office door one day."

That sounds a little lowtech, they can drop an email in your box, surely. This "common knowledge" is the strong impression one gets from the rabbinic literature, which often includes all sorts of interesting sociological tidbits.